This invention relates to a hydraulic torque impulse generator of the type comprising a drive member coupled to a rotation motor, a substantially cylindrical fluid chamber confined in said drive member, an output spindle provided with a rear impulse receiving portion which extends into said fluid chamber, and at least two radially slidable vanes carried by said rear spindle portion and arranged to cooperate sealingly with corresponding seal portions on the wall of said fluid chamber, at least two axially extending seal ribs on the fluid chamber wall and at least two axially extending seal ribs on the rear spindle portion arranged to cooperate with said seal ribs on the fluid chamber wall, said vanes, seal portions and seal ribs being arranged to divide said fluid chamber during two or more limited intervals of each revolution of said drive member relative to said output spindle into at least two high pressure compartments and at least two low pressure compartments.
The main object of the invention is to provide a hydraulic torque impulse generator of the above type with means by which the generation of more than one torque impulse per revolution of the drive member in relation to the output spindle is avoided.